DLA systems in GRB afterglows

To date, half a dozen DLAs have been detected in grb afterglows, but most have modest signal-to-noise ratios. Our detection of a DLA in the afterglow of grb 030323 is unambiguous: its neutral hydrogen column density is log N(HI)=21.90±0.07, higher than any (grb- or QSO-) DLA hi column density inferred directly from Lyα in absorption. We discuss several other properties such as the metallicity, the detection of fine-structure lines of siii, and our strong upper limit on the H₂ content. The grb afterglow allows us to infer all these quantities, even with the host being as faint as v=28. The successful launch of the swift satellite (november 2004) has made high-resolution spectroscopy of a large sample of grb afterglows possible. This will offer a unique way to study in detail the interstellar medium inside grb host galaxies as a function of redshift.